Development of plastics for food packaging

Development of plastics for food packaging

in recent years, due to the implementation of new measures such as strong alliance and transnational cooperation in the world packaging industry, the world packaging industry, especially food plastic packaging, has made great progress, and new materials, new processes, new technologies and new products continue to emerge

some European and American countries invested heavily in the development of non-polar and polar ethylene copolymers to improve the tensile and coextrusion properties of plastic films, improve transparency, enhance stability, and improve molecular weight distribution and extrusion rheological properties. In the contemporary injection molding process, countries are replacing LLDPE, PP, EVA and PVC with VLDPE (ultra low density polyethylene). In extrusion, injection molding and blow molding processes, VLDPE will occupy the flexible packaging market of medicine, medical treatment and cosmetics, and will impact the field of food packaging

experts believe that the development focus of the plastic industry in the contemporary world can realize a variety of safety protection methods such as overload, overcurrent, overvoltage, undervoltage, overspeed, limit and so on; It lies in the modification of plastics, the coating of plastic products, the rapid biodegradation of waste plastics, and the recycling of plastics. Some European and American manufacturers have used linear ethylene - α Ethylene vinyl acetate copolymer and ethylene vinyl acetate copolymer are mixed to produce PA bags, which are suitable for packaging ice cream, milk fat and other foods. It is particularly worth mentioning that pen (polyethylene naphthalate) "new polyester" packaging material attracts attention in the plastic packaging industry. Because the molecular structure of pen is similar to that of pet (polyethylene terephthalate), but the benzene ring is replaced by naphthalene ring, pen has better barrier property than pet, especially gas barrier property and UV resistance linearity, Its heat resistance is also good (the size of heat deformed samples and experimental force of ordinary amorphous pen vary greatly in structure. (samples with large experimental force generally adopt inclined clamping structure. With the addition of experimental force, the clamping force is added at a temperature of 100 ℃, while pet is only 70 ℃). With the industrialized production of pen, pen will enter the field of food packaging in a large number in the near future, triggering another packaging revolution after pet

metallocene is an organometallic coordination compound formed by the connection of transition metals and cyclopentadiene. Metallocene polyolefins are polymers prepared by olefin polymerization with metallocene coordination compounds as catalysts. Metallocene polymers have many advantages, such as good processability, high strength, high rigidity and transparency. It is qualified that the pressure drop within 15 minutes does not exceed 0.05Mpa, so they have attracted people's attention and many new varieties have been introduced

metallocene plastics will directly impact PP, MDPE, LLDPE, elastomer and other plastic markets. At present, the demand for PE in the world market is 40million tons, which is expected to increase to 50million tons by 2005. Most of the increase is metallocene polyethylene. Metallocene plastics have many advantages, such as good gloss, high melt strength and film stability, and are suitable for the field of food packaging

foreign countries have developed a large number of multifunctional composite membranes to further refine their functions, such as: the cold resistant membrane can withstand -18 ℃, -20 ℃, -35 ℃ low temperature environment; The series of moisture-proof films made of PP by moisture-proof treatment can be divided into moisture-proof, anti condensation, anti steam, adjustable moisture and other types; The anti-corrosion film can package perishable, acidic and sweet foods; Stable stacking of friction film; Special PE film corrosion resistance; Odorless insect repellent is added to the mothproof film; Whether the new material of Biaxially Stretched Nylon 66 heat-resistant film replacing biaxially stretched graphene can trigger an energy storage revolution has also attracted many attention. Long 6 film packaged food can withstand 140 ℃ high temperature; The fresh-keeping film has good sealing and mildew resistance, and there is no condensation and condensation; Water regulating membrane can absorb ethylene gas released by fruits; The new special food packaging film can improve the fragrance retention of food packaging; The transparency of amorphous nylon film is similar to that of glass; High shielding film can maintain the stability of color, aroma, taste, nutritional indicators and taste quality; The metal protective film adopts LDPE modified film to package liquid products, which can be heat sealed in low temperature environment

nowadays, some new plastic processes have been introduced abroad. In the European market, PVC transparent coiled material has been introduced to replace blow molding hollow containers, which can reduce the weight by 50%. In the 5-9 layer coextrusion film process, using recycled plastic as the intermediate layer can reduce the cost, and the layer thickness is controlled by micro processing feedback. Japan introduced the co extrusion process of pet and PC, which not only improved the heat resistance, impact resistance, pollution resistance and drug resistance, but also reduced the price. PP foaming shrinkage standard sleeve is used for glass bottles, which is suitable for 90 ℃ pasteurization hot filling. The UK launched special PP resin injection blow packaging bottles, which can achieve the purpose of light weight, high strength, uniform thickness and saving raw materials

nowadays, plastic cups and composite cups (outer PSP, inner PP, cover PS) are popular in foreign countries to package hot and cold drinks, wine and convenience food. France uses PE bottles to pack fructose and yogurt, while Germany uses PC bottles to pack milk. Some countries also use PE or its soft plastic barrels mixed with EVA to package drinks

at present, a large number of special plastic cover products suitable for various standards and uses are being developed in foreign countries. For example, Renault uses aluminum foil, paper and PE as bottle caps; In Europe, the aluminum cover is replaced by the heat shrinkable film cover; Japan introduced 280 ℃ high temperature resistant paint bottles and CPI paint aluminum foil covers with six series specifications for packaging lactic acid drinks